During rock drilling, shockwave pulses are generated in the form of pressure force pulses, which are transmitted from a shockwave creating device, such as a percussion device, through a drill string all the way to a drill bit. The buttons of the drill bit are thereby pressed with high intensity against the rock and accomplishes crushing and forming of crevices in the meeting rock.
In conventional rock drill machines shockwave pulses are generated by a percussive piston, which strikes against a drill shank for further transfer of the shockwave to the drill string. In convention rock drilling with rock drill machines including percussive pistons there are limited possibilities of controlling the shape of the shockwave.
The present invention relates to another type of shockwave producing machines, here called pulse machines (in rock drilling pulse drilling machines). These machines work differently from the machines mentioned above that are equipped with a percussive piston, to the extent that a pressure fluid is brought to create a force that periodically acts against a piston adapter in the form of an impulse piston, which in turn, in the case of a rock drilling machine, presses against and transmits shockwave pulses to a drill string. The impulse piston, which is not to be mistaken for the percussive piston in a conventional machine, has a relatively small mass, which does not have any influence of importance on the function of the pulse machine. As an example of the background of the invention, WO 2004/073933 could be mentioned.